5 files changed, 33 insertions, 34 deletions

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index db32a55daaec..cd241ee66eff 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -204,21 +204,6 @@ static __init void detect_diag9c(void)
 		S390_lowcore.machine_flags |= MACHINE_FLAG_DIAG9C;
 }
 
-static __init void detect_diag44(void)
-{
-	int rc;
-
-	diag_stat_inc(DIAG_STAT_X044);
-	asm volatile(
-		"	diag	0,0,0x44\n"
-		"0:	la	%0,0\n"
-		"1:\n"
-		EX_TABLE(0b,1b)
-		: "=d" (rc) : "0" (-EOPNOTSUPP) : "cc");
-	if (!rc)
-		S390_lowcore.machine_flags |= MACHINE_FLAG_DIAG44;
-}
-
 static __init void detect_machine_facilities(void)
 {
 	if (test_facility(8)) {
@@ -331,7 +316,6 @@ void __init startup_init(void)
 	setup_arch_string();
 	setup_boot_command_line();
 	detect_diag9c();
-	detect_diag44();
 	detect_machine_facilities();
 	save_vector_registers();
 	setup_topology();
diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 9e1660a6b9db..c3597d2e2ae0 100644
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -35,6 +35,7 @@ EXPORT_SYMBOL(_mcount)
 ENTRY(ftrace_caller)
 	.globl	ftrace_regs_caller
 	.set	ftrace_regs_caller,ftrace_caller
+	stg	%r14,(__SF_GPRS+8*8)(%r15)	# save traced function caller
 	lgr	%r1,%r15
 #if !(defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT))
 	aghi	%r0,MCOUNT_RETURN_FIXUP
diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index c07fdcd73726..77d93c534284 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -1303,18 +1303,28 @@ static void hw_perf_event_update(struct perf_event *event, int flush_all)
 		 */
 		if (flush_all && done)
 			break;
-
-		/* If an event overflow happened, discard samples by
-		 * processing any remaining sample-data-blocks.
-		 */
-		if (event_overflow)
-			flush_all = 1;
 	}
 
 	/* Account sample overflows in the event hardware structure */
 	if (sampl_overflow)
 		OVERFLOW_REG(hwc) = DIV_ROUND_UP(OVERFLOW_REG(hwc) +
 						 sampl_overflow, 1 + num_sdb);
+
+	/* Perf_event_overflow() and perf_event_account_interrupt() limit
+	 * the interrupt rate to an upper limit. Roughly 1000 samples per
+	 * task tick.
+	 * Hitting this limit results in a large number
+	 * of throttled REF_REPORT_THROTTLE entries and the samples
+	 * are dropped.
+	 * Slightly increase the interval to avoid hitting this limit.
+	 */
+	if (event_overflow) {
+		SAMPL_RATE(hwc) += DIV_ROUND_UP(SAMPL_RATE(hwc), 10);
+		debug_sprintf_event(sfdbg, 1, "%s: rate adjustment %ld\n",
+				    __func__,
+				    DIV_ROUND_UP(SAMPL_RATE(hwc), 10));
+	}
+
 	if (sampl_overflow || event_overflow)
 		debug_sprintf_event(sfdbg, 4, "%s: "
 				    "overflows: sample %llu event %llu"
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 2794cad9312e..a08bd2522dd9 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -413,14 +413,11 @@ EXPORT_SYMBOL(arch_vcpu_is_preempted);
 
 void smp_yield_cpu(int cpu)
 {
-	if (MACHINE_HAS_DIAG9C) {
-		diag_stat_inc_norecursion(DIAG_STAT_X09C);
-		asm volatile("diag %0,0,0x9c"
-			     : : "d" (pcpu_devices[cpu].address));
-	} else if (MACHINE_HAS_DIAG44 && !smp_cpu_mtid) {
-		diag_stat_inc_norecursion(DIAG_STAT_X044);
-		asm volatile("diag 0,0,0x44");
-	}
+	if (!MACHINE_HAS_DIAG9C)
+		return;
+	diag_stat_inc_norecursion(DIAG_STAT_X09C);
+	asm volatile("diag %0,0,0x9c"
+		     : : "d" (pcpu_devices[cpu].address));
 }
 
 /*
diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index da2d4d4c5b0e..707fd99f6734 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -36,10 +36,17 @@ static bool update_stack_info(struct unwind_state *state, unsigned long sp)
 	return true;
 }
 
-static inline bool is_task_pt_regs(struct unwind_state *state,
-				   struct pt_regs *regs)
+static inline bool is_final_pt_regs(struct unwind_state *state,
+				    struct pt_regs *regs)
 {
-	return task_pt_regs(state->task) == regs;
+	/* user mode or kernel thread pt_regs at the bottom of task stack */
+	if (task_pt_regs(state->task) == regs)
+		return true;
+
+	/* user mode pt_regs at the bottom of irq stack */
+	return state->stack_info.type == STACK_TYPE_IRQ &&
+	       state->stack_info.end - sizeof(struct pt_regs) == (unsigned long)regs &&
+	       READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE;
 }
 
 bool unwind_next_frame(struct unwind_state *state)
@@ -80,7 +87,7 @@ bool unwind_next_frame(struct unwind_state *state)
 			if (!on_stack(info, sp, sizeof(struct pt_regs)))
 				goto out_err;
 			regs = (struct pt_regs *) sp;
-			if (is_task_pt_regs(state, regs))
+			if (is_final_pt_regs(state, regs))
 				goto out_stop;
 			ip = READ_ONCE_NOCHECK(regs->psw.addr);
 			sp = READ_ONCE_NOCHECK(regs->gprs[15]);